Study finds some immunity to A/H1N1 virus

U.S. researchers have said that people who have had repeated flu infections, or repeated flu vaccines, may have some protection against the A/H1N1 virus.

The study, published in the Proceedings of the National Academy of Sciences, found evidence that the human immune system can recognize bits of the new A/H1N1 virus that are similar to older, distantly related A/H1N1 strains. It may explain why many older people are less likely to suffer severe symptoms, as they may have some pre-existing immunity for the flu.

Scientists said the result suggested that it could make the disease less severe in the general population than originally feared. But they stressed that people should still be vaccinated against A/H1N1.